Shell structure of wind turbine blade having regions of low shear modulus

Abstract

The torsional rigidity of a wind turbine blade affects the twist response of the blade induced by bending moments within the blade. By including regions having a lower modulus of rigidity than the remainder of the blade shell, the torsional rigidity of the blade shell can be decreased, and the twist response thereby increased. In blades having a single shear web, this twist response may be more pronounced. The regions of low modulus may comprise additional shell panels, or thick regions of low modulus joining material.

1. A wind turbine blade, comprising:
 a blade shell comprising at least a first shell section, a second shell section, and an intermediate shell section extending between the first shell section and the second shell section; 
 a stiffening structure disposed between said first shell section and said second shell section; 
 wherein the intermediate shell section comprises a material having a lower modulus of rigidity than the first shell section and the second shell section. 
 
     
     
       2. The blade of  claim 1 , wherein the intermediate shell section is configured to reduce the torsional stiffness of the blade shell. 
     
     
       3. The blade of  claim 2 , wherein the reduction in torsional stiffness increases a twist response of the blade. 
     
     
       4. The blade of  claim 1 , wherein the intermediate shell section is located at a trailing edge of the blade. 
     
     
       5. The blade of  claim 4 , wherein the intermediate shell section comprises an additional shell panel extending between the first shell section and the second shell section. 
     
     
       6. The blade of  claim 5 , wherein the additional shell panel extends along only a portion of the trailing edge. 
     
     
       7. The blade of  claim 5 , wherein the additional shell panel comprises a substantially flat panel extending in a direction substantially orthogonal to a plane of rotation of the blade. 
     
     
       8. The blade of  claim 1 , wherein the intermediate shell section is located near a leading edge of the blade. 
     
     
       9. The blade of  claim 8 , wherein the intermediate shell section is located adjacent the front stagnation zone. 
     
     
       10. The blade of  claim 1 , wherein the intermediate shell section comprises a layer of joining material having a low modulus of rigidity. 
     
     
       11. The blade of  claim 10 , wherein the first shell panel comprises an inward jog at the leading edge of the first shell panel, the inward jog configured to lie inward of a leading edge of the second shell panel, wherein the adhesive is disposed between the second shell panel and the inward jog of the first shell panel. 
     
     
       12. The blade of  claim 10 , wherein the layer of joining material is secured to the first and second shell sections via a thin layer of adhesive. 
     
     
       13. The blade of  claim 10 , wherein the layer of joining material comprises a rubberized material. 
     
     
       14. The blade of  claim 10 , wherein the layer of joining material comprises a layer of adhesive having a low modulus of rigidity. 
     
     
       15. The blade of  claim 10 , wherein the layer of joining material has a modulus of rigidity of less than 100 ksi. 
     
     
       16. A wind turbine blade, comprising:
 a blade shell, comprising: 
 a first shell panel; and 
 a second shell panel, wherein at least a portion of an edge of said first shell panel is configured to slidably interact with at least a portion of an edge of said second shell panel to reduce the torsional stiffness of the blade shell; and 
 a stiffening structure disposed between said first shell panel and said second shell panel. 
 
     
     
       17. The blade of  claim 16 , wherein said first shell panel comprises a rail disposed along at least part of a leading edge of said first shell panel, wherein said second shell panel comprises a groove disposed along at least part of a leading edge of said second shell panel, and wherein said rail is configured to slidably interact with said groove. 
     
     
       18. The blade of  claim 17 , additionally comprising a protective member between an exterior surface of said first shell panel and an exterior surface of said second shell panel, wherein the protective member extends over at least a portion of said groove and said rail. 
     
     
       19. The blade of  claim 16 , wherein said stiffening structure comprises a first spar cap disposed adjacent an interior surface of said first shell panel and a second spar cap disposed adjacent an interior surface of said second shell panel. 
     
     
       20. The blade of  claim 19 , wherein said stiffening structure further comprises a single shear web extending between said first spar cap and said second spar cap.